7.6.3 / 7.8.1 Install Landing Gear Hydraulic Cylinders

This entry is part 16 of 38 in the series 07 - Landing Gear

The hydraulic cylinders which actuate the nose and main landing gear are attached to the floor of the fuselage in positions called out in the manual. The holes for the mounts run through the floor and countersunk, flathead screws are used from the outside.

I also fabricated the two hydraulic lines that run between the hydraulic cylinders.

Nose gear cylinder

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Main gear cylinder

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7.1 Nose Gear Door Installation

This entry is part 17 of 38 in the series 07 - Landing Gear

The Nose Gear Doors are provided as a single assembly.  They will eventually be cut into two separate doors.

Earlier, I laminated many pieces of fiberglass to create the stock that the hinges would be made from.  These hinges are basically a “J-hinge” which are similar to the hinge arms used in doors and trunks of cars. They allow a form-fitting piece to swing away from the body without rubbing against it.

To install the doors, first they are bonded to the opening with auto-body filler (Bondo) to temporarily but firmly hold them in position while the hinges are positioned and permanently bonded into place.

Nose gear doors held in place with Bondo.

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Next, the hinges are aligned with lengths of all-thread and then the hinges are bonded to the gear door with an epoxy/cabo mix.

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Once the epoxy cures, the all thread is removed that then eight tabs (two for each hinge arm) that I cut out of fiberglass layups are used to create the fuselage side of the hinges are bonded to the fuselage. These tabs are custom fitted to the fuselage.  I numbered them to keep track of where they go and put a dot on the forward faces side. Once these cure, then the nose gear door can be removed and cut into two pieces, and the hinge arms and tabs can receive fiberglass layups to make them permanent.

Nose gear door (still one piece) with the tabs glued    in position.

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Close up of the rear portion of the door, hinge arms and tabs.

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7.1 Nose Gear Door Installation

This entry is part 18 of 38 in the series 07 - Landing Gear

Once the door hinge tabs had set up, I cut the nose gear door in half. A rather difficult task considering that I was doing it in a somewhat upside down position. But once they were in half, they can be removed and then reinforcement layups are put over the hinge arms and over the hinge tabs to the fuselage.

This the inside of the nose area with the doors removed and the layups on the outside of the hinge tabs.

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Closeup of the rear tabs.  I have to drill through the layups that cover the holes in the tabs.

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The (now two) nose gear doors with the layups over the hinge arms.

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7.6.1 Main Gear Pulley Installation

This entry is part 19 of 38 in the series 07 - Landing Gear

The main landing gear is retracted by the hydraulic cylinder pulling cables that attach to the top of the landing gear. This cable has to pass through a pair of pulleys at the center of the main gear bulkhead.

The mounting hardware is temporarily held in place and string is used to insure the path of the cables does not rub or bind between where the cylinder is and the top of the gear leg. Once the location has been determined, holes are drilled through the bulkhead.

In this picture, the pulley has been removed.

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The carpet really helps when you are kneeling.

 

7.6.1 Main Gear Pulley Installation

This entry is part 20 of 38 in the series 07 - Landing Gear

Because of the amount of force the main gear pulleys receive, a significant amount of reinforcement is needed. This is accomplished with a pair of gussets on either side of the pulleys and numerous layups.

Gussets and layups.

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Once cured, the pulleys are installed and checked for fit, remove, file some of the bulkhead away to allow movement, put the pulleys back in place and repeat… multiple times. This took most of the day.

But eventually, its cleaned up and the pulley assembly is permanently installed.

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7.2.1 Nose Gear Installation

This entry is part 21 of 38 in the series 07 - Landing Gear

The hole for the nose gear pivot was drilled out earlier. Now the bushings have to be installed. There’s a plate on the inside and outside for each side of the nose gear pivot which gets held in place with structural adhesive and fours bolts (per side).

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Once the main pivot had set up, I had to insure the rear pivot point was correctly located. It was. This is the second mounting location that hasn’t required any adjustment. I’m told that they almost always need to be moved a little. This makes me a bit apprehensive. When thing go together too well, I usually think it means that I’m overlooking something. But Scott Swing said it was good so I used epoxy to hold the bushings and mounting plate is place.

Then the hydraulic cylinder is attached.

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Almost ready for a nose wheel.

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7.2.1 Nose Gear Installation

This entry is part 22 of 38 in the series 07 - Landing Gear

The final task in completing the nose gear is to install a “captivator” bracket and an upstop. The captivator prevents the nose gear from moving side-to-side when extended. The upstop limits how far the nose gear extends.

The captivator bracket install took almost a whole day. Even with a special tool that Scott made to assist. The two challenges are that the bracket has to be located in a very precise location which can only be determined when the nose gear is down.  But that prevents you from getting to the bracket to drill the mounting holes. The second challenge is there’s just not much room inside the keel.

The upstop was relatively easy.  Just a U-shaped piece of aluminum bolted in to the top of the keel. But once that was done, the airplane was sitting on all three wheels.

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7.4.1 Gear Leg Cut Out

This entry is part 23 of 38 in the series 07 - Landing Gear

I decided to continue with the last thing I was working on in Florida (Main Landing Gear – MLG). When they build the fuselage, They mount the MLG but only to the point that they can roll the fuselage around. They won’t retract. The first task was open up the side of the fuselage so the legs could come up.

Here’s the left side main gear leg.

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You’ll notice where the leg exits the fuselage, there’s an opening that’s a little bigger than the leg itself. When the gear is raised, that leg will swing up. But the hole isn’t big enough to allow that which means it has to be… bigger. But how big? Here’s my first dilemma: The book doesn’t really say. I was expecting a template that you would lay against the side and mark where to cut. Nope. No template. The book just says cut it, not how big. I’m a little nervous cutting when I don’t know where to cut so I fussed about this quite a bit. Down in Florida, I would have looked at another plane or asked someone and have been done. Instead, I reread the manual about 30 times, looked at pictures on other builders websites and read the manual again thinking I overlooked something. Finally, I just raised the leg and cut a little. And repeated this maybe 12 times until the leg would raise the correct amount.

This the result of 2 hours of research and 45 minutes of cut, check, cut, check, cut check…

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Gear leg up. (I removed the wheel to make it easier to work with.)

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Once I knew how big the opening needed to be, the other side took about 15 minutes. This is where the time black hole is going to come from. The whole task is probably slated to take 30 minutes for both sides, but it took me over 3 hours.

7.2.5 Nose Gear Guides

This entry is part 24 of 38 in the series 07 - Landing Gear

Here’s a picture of the nose gear retracted.

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If the nose gear gets turned while it’s retracted, the metal “fork” will catch on the edge of the opening and won’t be able to extend (I’ve been there before and it ain’t fun!).

To prevent this from happening, two “guides” are made to keep the nose gear from rotating once it’s retracted. The guides are made by creating flat, 1/8″ thick layups and letting them cure. Then cutting them out and attaching them to create the guides.

Once the layups cured, I cut out the guides and supports for the left and right.

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Then the supports are attached to the guides with 5-minute epoxy. When that sets up 2 BID layups are used to permanently attach the supports to the guides.

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Once those layups cure, they’re trimmed and then the guides are fitted to the opening in the nose with 5-minute epoxy. When that cures, a radius is created with micro and 2 BID attaches the guides to the fuselage.

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Trimmed and ready to go.

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7.8.1 Hydraulic Power Pack Installation

This entry is part 25 of 38 in the series 07 - Landing Gear

Then I went to mount the hydraulic pump assembly. This is an electric motor mounted to a pump which is mounted to a reservoir. But when I tried to mount it, the tabs didn’t meet the bulkhead… The reservoir was in the way.

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Here you can see the two mounting holes that I think should fit against the bulkhead. I checked pictures from some other builders and it seems I’m right.

Here’s another builders bulkhead with attached pump.

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But after I emailed the factory, I was told that I need a bracket. So now I’ve got to wait for that.